Spatial Variability of Selected Soil Properties of the Lower Niger River Floodplains in Bayelsa State, Nigeria

Abstract

Owing to the influence of topography on soil properties, studies on the variability of soil properties become imperative. This study assessed spatial variability of some selected soil properties in three physiographic units: upper slope, lower slope and recent alluvial soils on channels of present active river in two locations in Bayelsa State. In each unit, one representative soil profile was dug, soil samples collected from generic horizons and analyzed. The results showed varying degree of spatial variability in physical and chemical characteristics, flooding, the source of parent materials and degree of hydromorphism; being the major determining factors. Among the soil separates, clay was highly variable in two physiographic units while sand and silt showed moderate variability. Organic C was moderately to highly variable (CV=20.13 – 112.77%), while total N (36.53 – 90.01%) and available P (41.49 – 58.71%) were highly variable in all the mapping units. Calcium was moderately variable (CV=26.85%) in the upper slope, and highly variable in the middle slope (CV=43.17%) and moderately variable (CV=28.93%) in recent alluvial soils in the channel of the present active river of Elemebiri and in Trofani soils; low (CV=10.01%) in the upper slope, highly variable (CV=41.33%) in the middle slope and moderately variable (CV=22.08%) recent alluvial soils in the channel of the present active river while Mg (CV=66.79 – 80.29%) and K (CV=39.27 – 101.53%) were highly variable in the different physiographic units of the two locations. Flooding, wetness and soil fertility are major constraints to agricultural intensification that requires attention.